Method for manufacturing a prosthetic hip acetabulum

ABSTRACT

A method for manufacturing a prosthetic hip acetabulum includes the steps of: a) providing an insertion cup ( 1 ) having an inner concave receiving surface ( 3 ) having an opening surface ( 5 ) contained in an opening plane (P), and having an outer annular receiving structure ( 6 ); b) providing an installation and positioning insert ( 7 ) having a peripheral annular attachment structure ( 10 ) shaped to engage with the receiving surface ( 9 ) of the outer annular receiving structure ( 6 ) fitting around the annular outer receiving structure ( 6 ); c) heating the installation and positioning insert ( 7 ) in order to increase the size of the insert ( 7 ), d) fitting the peripheral annular attachment structure ( 10 ) around the receiving surface ( 9 ) of the outer annular receiving structure ( 6 ); e) cooling the installation and positioning insert ( 7 ) to room temperature in order to reduce the size of the insert ( 7 ) and achieve radial tightening of the peripheral annular attachment structure ( 10 ) on the outer annular receiving structure ( 6 ).

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method for manufacturing a prostheticacetabulum intended to replace the natural acetabulum of the hip.

A total hip prosthesis comprises two parts constituting aball-and-socket joint, namely a female part intended to replace thenatural acetabulum of the hip, and a male part intended to replace thehead of the femur. The male part of the joint generally has a shaftwhich is intended to engage in the medullary canal of the femur and ofwhich the proximal end is connected by a neck to a spherical headintended to engage in the female part. The female part of the joint,which has to replace the natural acetabulum of the hip, usuallycomprises a substantially hemi-spherical insertion cup, which isaccommodated in a prepared acetabular cavity in the pelvic bone. Theinsertion cup is usually made of metal.

When fitting the insertion cup in the acetabular cavity, it must bepossible to use an impactor for holding and manipulating the insertioncup and for applying a force to drive the cup into the acetabular cavityin the bone with a good orientation and for long enough for a cement toset between the outer surface of the insertion cup and the acetabularcavity of the bone.

The document FR 2 909 541 A1 describes an insertion cup with a convexand hemispherical outer anchoring face. To hold this cup during itsimpaction, an outer annular groove is provided near its free annularedge. This annular groove permits the fixation of an impactor comprisinga main body with at least two hook-shaped elastic tabs.

In this document, the force with which the cup is retained by theimpactor is in correlation with and substantially equal to the forcethat has to be applied to spread apart the elastic tabs. This means thatthe better the hold of the cup by the impactor, the more difficult it isto spread the tabs apart, and this causes the user more effort to fixthe impactor to the cup.

There is a need to permit easy fixation of an impactor to a cup whileproviding a reliable hold of the cup.

The document WO 2006/040483 A1 describes a prosthetic hip acetabulumcomprising an insertion cup with:

-   -   a substantially hemispherical convex outer anchoring face        designed to be anchored in an acetabular cavity of the pelvis of        a patient,    -   a concave inner receiving face with an annular edge and with an        opening face that is contained in an opening plane,    -   an annular receiving structure designed in such a way that an        impactor can be fixed to said annular receiving structure for        impaction of the cup in the acetabular cavity of the pelvis of a        patient.

In the document WO 2006/040483 A1, the installation and orientationinsert is cooled so as to contract and permit its introduction into theinsertion cup, and it is then brought back to room temperature in orderto expand and attach itself strongly to the insertion cup. In order tosufficiently reduce the dimensions of the installation and orientationinsert, the latter is cooled in a refrigerated vessel. The presence ofliquid has sometimes been observed inside the refrigerated vessel,resulting from a condensation phenomenon. Condensate liquidscontaminated by bacteria or microbes can thus form and/or settle on theinstallation and orientation insert, which then contaminates theinsertion cup after the installation and orientation insert and theinsertion cup have been joined together. This is particularly criticalwhen the installation and orientation insert is made of plastic: theplastics that can be used for the installation and orientation insert,for example polyethylene, have a tendency to absorb the liquids. Thereis therefore a risk that the installation and orientation inserts madeof plastic will absorb condensate liquids contaminated by bacteria ormicrobes, which then causes deep-rooted contamination of theinstallation and orientation inserts.

Moreover, it is also expedient to provide, between the cup and theimpactor, a stronger join than is made possible by the teaching of thedocument WO 2006/040483 A1.

SUMMARY OF THE INVENTION

A problem addressed by the invention is that of making available amethod for manufacturing a prosthetic hip acetabulum with insertion cupthat can be fixed more reliably and more firmly to an impactor, whilelimiting the forces to be applied and avoiding any risk ofcontamination.

To achieve these objects, and others, the invention proposes amanufacturing method comprising the steps of:

-   -   a) providing an insertion cup having a concave inner receiving        face with an opening face contained in an opening plane, and        having an outer annular receiving structure,    -   b) providing an installation and orientation insert having a        peripheral annular fixing structure designed to cooperate with        the receiving face of the outer annular receiving structure by        engaging around the outer annular receiving structure,    -   c) heating the installation and orientation insert in order to        increase the dimensions thereof,    -   d) engaging the peripheral annular fixing structure around the        receiving face of the outer annular receiving structure,    -   e) bringing the installation and orientation insert back to room        temperature in order to reduce the dimensions thereof, so as to        achieve a radial clamping of the peripheral annular fixing        structure on the outer annular receiving structure.

Such a manufacturing method makes it possible to obtain satisfactoryradial clamping of the installation and orientation insert on theinsertion cup.

The engagement of the installation and orientation insert around theouter annular receiving structure takes place without too much force, onaccount of the expansion of the installation and orientation insert byheating.

However, the separation of the cup and the installation and orientationinsert requires substantial forces after cooling, and this permitssatisfactory impaction and orientation of the cup.

The forced retention of the installation and orientation insert on theinsertion cup by radial clamping ensures reliable and secure fixation,by means of which it is possible to withstand the forces applied duringthe impaction of the insertion cup. The radial clamping of theperipheral annular fixing structure on the outer annular receivingstructure makes it possible to achieve this reliable fixation withoutover-complicating the shape of the outer annular receiving structure.

The retention of the installation and orientation insert on theinsertion cup is more reliable than that of document WO 2006/040483 A1,especially by virtue of the fact that the radial clamping takes place onan annular receiving structure which is external and which thus has agreater contact surface with the installation and orientation insert.

Finally, the radial clamping of the peripheral annular fixing structureon the outer annular receiving structure induces a state of prestressingin the insertion cup, and this prestressing limits the risks ofdeformation of the insertion cup during its impaction in the acetabulumof the pelvis of a patient. The reason is that, when the insertion cuphas a relatively small thickness near its upper annular edge, forexample of less than 3 mm, phenomena of ovalization of the insertion cupsometimes occur (if the insertion cup is made of a deformable materialsuch as metal or plastic for example), and these phenomena then make itimpossible for the male part of the prosthetic joint to engage in theinsertion cup, or they generate unequally distributed internalmechanical stresses likely to lead to the breakage of the insertion cup(if the latter is made of a weak material such as ceramic for example)or generate unequally distributed internal mechanical stresses likely tosubsequently damage the articular insert, especially if the latter ismade of ceramic.

In the manufacturing method of the present invention, by means ofproviding an insertion cup having an outer annular receiving structureon which an installation and orientation insert is clamped by beingbrought back to room temperature after expansion by heating, it ispossible to avoid the problem of contamination of the installation andorientation inserts, especially when these are made of polyethylene.

Within the context of the present invention, the concave inner receivingface can be a slide face for receiving an articular insert that ismovable with respect to the insertion cup (for an acetabulum with dualmobility for example) or can be designed to receive an articular insertthat is stationary with respect to the insertion cup (for an acetabulumwith single mobility for example).

Advantageously, before fixing the installation and orientation insert onthe insertion cup, the method can comprise the supplementary step b1) ofinserting an articular insert in the concave inner receiving face of theinsertion cup.

The insertion cup, the articular insert and the installation andorientation insert can thus be pre-assembled at the place ofmanufacture, such that the surgeon simply has to impact the unit thusformed without having to concern himself with the articular insert. Inaddition, the articular insert can then be positioned correctly in theinsertion cup without any involvement of the surgeon. This thereforelimits the risks of poor positioning of the articular insert in theinsertion cup, which can lead to premature breaking of the articularinsert.

Advantageously, provision can be made that:

-   -   the articular insert is made of ceramic,    -   the installation and orientation insert has elastic means for        holding the articular insert in the insertion cup,    -   when the installation and orientation insert is fixed to the        insertion cup, the installation and orientation insert comes        into contact with the articular insert only via the elastic        means for holding the articular insert in the insertion cup.

The elastic holding means keep the articular insert correctly positionedin the insertion cup during transport and storage and when being handledby the surgeon. When the surgeon applies an impaction force on theinsertion cup by way of the installation and orientation insert, noshock will be transferred to the ceramic articular insert, since theelastic holding means will deform. There is therefore no risk of thesurgeon breaking the ceramic articular insert during the impaction.

Advantageously, the method can additionally have a step f) during whichthe unit thus formed and packed in a microbial protection envelope issterilized.

Preferably, provision can be made that the articular insert is made ofceramic, and that the step f) of sterilization is carried out bybombardment with gamma rays, advantageously at a dose of betweenapproximately 25 kGy and approximately 40 kGy.

In the document WO 2006/040483 A1, the annular receiving structurecomprises a cylindrical or slightly conical annular retention surfacethat continues the surface of the concave inner receiving face.

However, this substantially cylindrical continuation limits the possibleangular clearance of the prosthetic femoral shaft. In addition, thecylindrical continuation increases the risk that the prosthetic femoralshaft, which is generally made of metal, comes into contact with theinsertion cup. In the event of such contact, if the insertion cup ismade of metal, a phenomenon of metallosis occurs through degradation ofthe edge of the insertion cup and/or of the prosthetic femoral shaft.This degradation produces metal debris that can impregnate thesurrounding tissues and/or damage the prosthesis. Moreover, when the cupis not made of metal, and is in particular made of ceramic or a plasticsuch as PEEK for example, there is a risk of partial or total breakageof the insertion cup.

This is why the annular receiving structure can preferably be externaland be situated set back from the opening plane.

When the annular receiving structure for fixation of the impactor issituated set back from the opening plane, in the direction of the summitof the substantially hemispherical convex outer anchoring face, thisannular receiving structure no longer limits the angular clearance ofthe prosthetic femoral shaft that will be fitted. At the same time, therisk of contact between the prosthetic femoral shaft and the edge of theinsertion cup is limited, thereby reducing the risk of metallosis and/orbreakage.

Preferably, the installation and orientation insert can have an assemblystructure on which an impactor can be fixed removably.

It is thus possible to mount the installation and orientation insert onthe insertion cup at the place of manufacture, such that the surgeonthen simply has to fix the impactor on the installation and orientationinsert in order to perform impaction of the insertion cup. There is norisk of the surgeon damaging the concave inner receiving face of theinsertion cup, the latter being protected by the installation andorientation insert.

Advantageously, provision can be made that:

-   -   the outer annular receiving structure comprises a continuous or        interrupted peripheral radial shoulder of the annular edge, with        a receiving face directed toward the outside,    -   the installation and orientation insert has a continuous or        interrupted peripheral annular fixing structure with a        connecting face directed toward the inside and designed to        cooperate with the receiving face of the outer annular receiving        structure.

According to a first variant, provision can be made that:

-   -   the receiving face of the outer annular receiving structure has        an interrupted peripheral locking groove,    -   the connecting face of the peripheral annular fixing structure        of the installation and orientation insert has a plurality of        locking ribs distributed peripherally and designed so as to        engage in the interrupted peripheral locking groove.

According to a second variant, provision can be made that:

-   -   either the receiving face of the outer annular receiving        structure or the connecting face of the peripheral annular        fixing structure has a continuous peripheral annular locking        groove,    -   the other of the connecting face of the peripheral annular        fixing structure or the receiving face of the outer annular        receiving structure has a continuous or interrupted peripheral        annular locking rib designed so as to engage in the continuous        peripheral annular locking groove.

The locking groove and the one or more locking ribs participate inretaining the installation and orientation insert on the insertion cup.This also greatly increases the strength of the join between theinstallation and orientation insert and the insertion cup in order towithstand orientation torques that the surgeon transfers by way of theimpactor.

Advantageously, provision can be made that:

-   -   the peripheral radial shoulder of the annular edge has a        thickness of between approximately 0.7 mm and approximately 1.2        mm,    -   said interrupted peripheral locking groove or said continuous        peripheral annular locking groove of the outer annular receiving        structure has a radial thickness of between approximately 0.2 mm        and approximately 0.6 mm.

Such dimensions are compatible with an insertion cup having a smallthickness near its upper annular edge, for example of less than 3 mm.The use of an insertion cup having a small thickness near its upperannular edge makes it possible to increase the diameter of the sphericalhead of the male part of the joint and thus limit the risk ofdislocation.

Preferably, provision can be made that the peripheral radial shoulder ofthe annular edge has a height of between approximately 1 mm andapproximately 4 mm.

Such a height of the peripheral radial shoulder provides a sufficientcontact surface between the installation and orientation insert and theinsertion cup for the radial clamping, without thereby excessivelydiminishing the surface area of the convex outer anchoring face intendedto come into contact with the bone. This is all the greater in view ofthe fact that the outer anchoring surface part situated substantially inthe vicinity of the equatorial plane thereof is a part that participatessubstantially in the retention of the insertion cup in the acetabularcavity of the pelvis.

Advantageously, provision can be made that said interrupted peripherallocking groove or said continuous peripheral annular locking groove ofthe outer annular receiving structure has a height of betweenapproximately 0.4 mm and approximately 3 mm.

Preferably, provision can be made that the installation and orientationinsert and the outer annular receiving structure of the insertion cupare designed in such a way that, when the installation and orientationinsert is fixed on the outer annular receiving structure of theinsertion cup, the installation and orientation insert does not protrudeoutside a substantially hemispherical surface defined by thesubstantially hemispherical convex outer anchoring face of the insertioncup. This therefore avoids any risk of conflict of the installation andorientation insert with the bone substance present near the preparedacetabular cavity of the pelvis of the patient.

Advantageously, the peripheral annular fixing structure of theinstallation and orientation insert can have a radial thicknesssubstantially equal to or less than the thickness of the radial shoulderof the annular edge.

Preferably, the installation and orientation insert can be made ofpolyethylene. Polyethylene is commonly used in the medical field and isinexpensive and easy to machine. Moreover, polyethylene does not riskdamaging an insertion cup made of metal, of ceramic, of PEEK or of amaterial harder than polyethylene.

Preferably, the assembly structure can comprise a fixation hole withinternal thread made in the installation and orientation insert,permitting the screwing of a corresponding threaded portion of theimpactor.

Advantageously, the fixation hole can be a through-hole able tocooperate with a disconnecting tool that has a threaded rod able to bescrewed into the through-hole and which has a distal end designed tobear, directly or indirectly, against the concave inner receiving faceof the insertion cup when the threaded rod is screwed into thethrough-hole.

Preferably, provision can be made that:

-   -   the installation and orientation insert is designed in such a        way that a free space remains between the installation and        orientation insert and the bottom of the concave inner receiving        face, or, if appropriate, between the installation and        orientation insert and the articular insert, once the        installation and orientation insert is fixed to the outer        annular receiving structure of the insertion cup,    -   the installation and orientation insert bears in a sealed manner        across its connecting face against the receiving face of the        outer annular receiving structure,    -   the fixation hole is a through-hole via which the free space        between the installation and orientation insert and the bottom        of the concave inner receiving face or, if appropriate, between        the installation and orientation insert and the articular insert        is brought into communication with the outside and which is        dimensioned for leaktight engagement of the end of a syringe.

BRIEF DESCRIPTION OF THE DRAWINGS

Other subjects, features and advantages of the present invention willbecome clear from the following description of particular variants, saiddescription making reference to the attached figures, in which:

FIG. 4 is a perspective view of an insertion cup of a prostheticacetabulum according to a first variant of the invention;

FIG. 5 is a side view of the cup from FIG. 4;

FIG. 6 is a perspective view of an installation and orientation insertintended to be joined to the insertion cup from FIGS. 4 and 5;

FIG. 7 is a sectional view of the installation and orientation insertfrom FIG. 6;

FIG. 8 is a perspective view of an installation and orientation insertand of an insertion cup of a prosthetic hip acetabulum according to asecond variant of the invention;

FIG. 9 is a sectional view of the installation and orientation insertfrom FIG. 8;

FIG. 10 is a partial sectional view of the insertion cup from FIG. 8;

FIG. 11 is a partial sectional view of the installation and orientationinsert from FIG. 9;

FIG. 12 is a partial sectional view of the insertion cup and of theinstallation and orientation insert from FIGS. 10 and 11;

FIG. 13 is a perspective view of the insertion cup and of theinstallation and orientation insert from FIG. 8, with a stationaryarticular insert;

FIG. 14 is a sectional view of the elements from FIG. 13 once they havebeen assembled; and

FIG. 15 is a sectional view of an insertion cup and of an installationand orientation insert once they have been assembled.

Some of the attached figures illustrate subject matter that is not partof the present invention but that is described below and that may formthe subject of independent protection. These figures are the following:

FIG. 1, which is a perspective view of an insertion cup of a prostheticacetabulum;

FIG. 2, which is a perspective view of an installation and orientationinsert intended to be joined to the insertion cup from FIG. 1; and

FIG. 3, which is a sectional view of the installation and orientationinsert from FIG. 2.

DESCRIPTION OF PREFERRED EMBODIMENTS

Each one of FIGS. 1, 4, 5 and 8 shows an insertion cup 1 of a prosthetichip acetabulum. This insertion cup 1 comprises:

-   -   a substantially hemispherical convex outer anchoring face 2,        designed to be anchored in a prepared acetabular cavity of the        pelvis of a patient, and a concave inner receiving face 3, with        an annular edge 4 and with an opening face 5 that is contained        in an opening plane P,    -   an annular receiving structure 6 designed in such a way that an        impactor can be fixed to said annular receiving structure 6 for        the impaction of the insertion cup 1 in the acetabular cavity of        the pelvis of a patient.

The annular receiving structure 6 is external and is situated set backfrom the opening plane P. In other words, the annular receivingstructure 6 is offset, with respect to the opening plane P, in thedirection of the summit S of the outer anchoring face 2.

The annular receiving structure 6 is therefore not situated in thecontinuation of the inner receiving face 3 continuing the latter pastthe summit S. It is thus possible to avoid limiting the angularclearance of the prosthetic femoral shaft, and the risk of metallosisand/or breakage is reduced.

FIGS. 2, 3, 6, 7 and 9 show an installation and orientation insert 7intended to be joined to an insertion cup 1. The installation andorientation insert 7 of FIGS. 2 and 3 is intended to be joined to theinsertion cup 1 from FIG. 1. The installation and orientation insert 7of FIGS. 6 and 7 is intended to be joined to the insertion cup 1 fromFIGS. 4, 5 and 8. The installation and orientation insert 7 of FIG. 9 isintended to be joined to the insertion cup 1 from FIG. 8 .

Each installation and orientation insert 7 can be fixed removably to theouter annular receiving structure 6 of the insertion cup 1 and has anassembly structure 8 on which an impactor can be removably fixed.

In FIGS. 1, 5 and 8, it will be seen that the outer annular receivingstructure 6 comprises a continuous or interrupted peripheral radialshoulder d of the annular edge 4, with a receiving face 9 directedtoward the outside. It will be seen in FIGS. 2, 3, 6, 7 and 9 that eachinstallation and orientation insert 7 has a continuous or interruptedperipheral annular fixing structure 10 with a connecting face 11directed toward the inside and designed to cooperate with the receivingface 9 of the outer annular receiving structure 6.

In the subject matter of FIGS. 1 to 3, the receiving face 9 of the outerannular receiving structure 6 has an external thread 12, while theconnecting face 11 of the peripheral annular fixing structure 10 of theinstallation and orientation insert 7 has an internal thread 13 designedto cooperate with the external thread 12 by screwing.

The subject matter of the present invention is illustrated in FIGS. 4 to13. In these figures, the outer annular receiving structure 6 and theperipheral annular fixing structure 10 are designed in such a way thatthe installation and orientation insert 7 is engaged with force aroundthe outer annular receiving structure 6 and is retained forcibly by aradial clamping of the peripheral annular fixing structure 10 on theouter annular receiving structure 6.

In order to further improve the hold of the installation and orientationinsert 7 on the insertion cup 1, a supplementary cooperation can beprovided between the installation and orientation insert 7 and theinsertion cup 1 by means of one or more locking ribs that engage in alocking groove.

In a first variant, illustrated in FIGS. 4 to 7, provision is made that:

-   -   the receiving face 9 of the outer annular receiving structure 6        has an interrupted peripheral locking groove 14;    -   the connecting face 11 of the peripheral annular fixing        structure 10 of the installation and orientation insert 7 has a        plurality of locking ribs 15 a to 15 d which are distributed        about the periphery and are designed so as to engage in the        interrupted peripheral locking groove 14.

In a second variant, illustrated in FIGS. 8 and 9, the receiving face 9of the outer annular receiving structure 6 has a continuous peripheralannular locking groove 16, while the connecting face 11 of theperipheral annular fixing structure 10 has a continuous peripheralannular locking rib 17 designed so as to engage in the continuousperipheral annular locking groove 16.

In this second variant, it is also possible that the connecting face 11of the peripheral annular fixing structure 10 has an interruptedperipheral annular locking rib. The installation and orientation insert7 can then be similar to that of the first variant of the secondembodiment of the invention, illustrated in FIGS. 6 and 7.

FIG. 10 is a partial sectional view of the annular edge 4 of theinsertion cup 1 from FIG. 8. It will be seen more particularly in FIG.10 that the outer annular receiving structure 6 comprises a peripheralradial shoulder d with a receiving face 9 directed toward the outside.The peripheral radial shoulder d has a thickness e1 of betweenapproximately 0.7 mm and approximately 1.2 mm.

The receiving face 9 has the continuous peripheral annular lockinggroove 16. The continuous peripheral annular locking groove 16 has aradial thickness e2 of between approximately 0.2 mm and approximately0.6 mm.

The insertion cup 1 has a thickness e4 near its annular edge 4. Thethickness e4 can be small, for example less than 3 mm.

The peripheral radial shoulder d of the annular edge 4 has a height hlof between approximately 1 mm and approximately 4 mm.

Finally, the continuous peripheral annular locking groove 16 has aheight h2 of between approximately 0.4 mm and 3 mm.

All the dimensions given above in connection with the second variant arevalid for the first variant and also for the subject matter of FIGS. 1to 3.

As will be seen from FIG. 11, the peripheral annular fixing structure 10of the installation and orientation insert 7 has, with its connectingface 11 and its continuous peripheral annular locking rib 17, a shapeand dimensions matching the receiving face 9 and the continuousperipheral annular locking groove 16. The installation and orientationinsert 7 and the insertion cup 1 can thus be joined very intimately, asis illustrated in FIG. 12.

In order to avoid any conflict of the installation and orientationinsert 7 with the bone substance around the natural acetabular cavity ofthe pelvis of the patient, the installation and orientation insert 7 andthe outer annular receiving structure 6 of the insertion cup 1 aredesigned in such a way that, when the installation and orientationinsert 7 is fixed to the outer annular receiving structure 6 of theinsertion cup 1, the installation and orientation insert 7 does notprotrude outside a substantially hemispherical surface S1 (illustratedby broken lines in FIG. 12) defined by the substantially hemisphericalconvex outer anchoring face 2 of the insertion cup 1.

To do this, the peripheral annular fixing structure 10 of theinstallation and orientation insert 7 has a radial thickness e3substantially equal to or less than the thickness el of the radialshoulder d of the annular edge 4.

So as not to risk damaging the insertion cup 1, the installation andorientation insert 7 is advantageously made of plastic, preferably ofpolyethylene, which is an inexpensive material that is easy to machine.

Within the context of the invention, the concave inner receiving face 3can be a slide face 3 a for receiving a movable articular insert, forexample for an acetabulum with dual mobility. In this case, the slideface 3 a is intended to receive a spherical movable articular insert(FIG. 15).

Still within the context of the invention, the concave inner receivingface 3 can be designed to receive a stationary articular insert 18, forexample for an acetabulum with single mobility, as is illustrated inFIG. 14. The stationary articular insert 18 is immobilized in theinsertion cup 1 by a conical engagement.

It will be seen more particularly in FIG. 14 that it is possible, at theplace of manufacture, to carry out pre-assembly and sterile packaging ofthe articular insert 18 engaged in the insertion cup 1 with theinstallation and orientation insert 7 fixed to the insertion cup 1. Thisresults in a pre-assembled unit ready for impaction by the surgeon, as aresult of which the operating times can be reduced. In addition, thearticular insert 18 is already fitted in the correct place in theinsertion cup 1, which limits the risk of poor positioning thereof bythe surgeon. This is particularly important when the articular insert 18is made of ceramic, since poor positioning then very often leads topremature breaking of the ceramic.

It will be seen more particularly in FIG. 14 that the installation andorientation insert 7 has elastic means 19 for holding the ceramicarticular insert 18 in the insertion cup 1. The elastic means 19 preventany displacement of the articular insert 18 in the insertion cup 1during transport, storage and handling of the pre-assembled insertioncup and articular insert 18.

So as not to risk damaging the ceramic articular insert 18 duringimpaction of the insertion cup 1, when the installation and orientationinsert 7 is fixed to the insertion cup 1, the installation andorientation insert 7 comes into contact with the articular insert 18only via the elastic holding means 19. It will be seen more particularlyin FIG. 12 that the installation and orientation insert 7 is designed insuch a way that a space E remains between the installation andorientation insert 7 and the articular insert 18. Therefore, noimpaction shock is transferred to the ceramic articular insert 18, whichis held in the bottom of the insertion cup 1 by the elastic means 19.

It will be seen more particularly in FIGS. 14 and 15 that the assemblystructure 8 of the installation and orientation insert 7 comprises afixation hole 20 with internal thread 21. The internal thread 21 permitsthe screwing of a corresponding threaded portion of the impactor (notshown).

After the impaction of the insertion cup 1 in the acetabular cavity ofthe pelvis of the patient, it is necessary to withdraw the installationand orientation insert 7. This withdrawal has to be performed withoutinducing stresses between the outer anchoring face 2 and the acetabularcavity of the pelvis of the patient, so as not to destroy the join madebetween them during the impaction.

A first solution to permit separation thus consists in the fixation hole20 being a through-hole that is able to cooperate with a disconnectingtool having a threaded rod with a distal end designed to bear directlyor indirectly against the concave inner receiving face 3 of theinsertion cup 1 when the threaded rod is screwed into the through-hole.In FIGS. 14 and 15, the fixation hole 20 has a first portion 20 a ofdiameter D1 and a second portion 20 b of smaller diameter D2. Thethreaded rod of the disconnecting tool has an external diameter designedsuch that it can be screwed into the portion 20 b of diameter D2 of thefixation hole 20.

A second solution permitting separation is one in which:

-   -   the installation and orientation insert 7 is designed such that        a free space E1 remains between the installation and orientation        insert 7 and the bottom of the concave inner receiving face 3        (FIG. 15) or, if appropriate, between the installation and        orientation insert 7 and the articular insert 18 (FIG. 14), once        the installation and orientation insert 7 is fixed to the outer        annular receiving structure 6 of the insertion cup 1,    -   the installation and orientation insert 7 bears in a sealed        manner across its connecting face 11 against the receiving face        9 of the outer annular receiving structure 6,    -   the fixation hole 20 is a through-hole via which the free space        E1 is brought into communication with the outside and which is        dimensioned for leaktight engagement of the end of a syringe.

In the case of FIGS. 14 and 15, the syringe end has an external diameterdesigned to engage in a leaktight manner in the portion of diameter D2of the fixation hole 20.

A liquid such as water or physiological saline is thus injected atpressure into the free space E1 in order to induce a force of separationbetween the insertion cup 1 and the installation and orientation insert7.

In order to obtain a sealed contact between the installation andorientation insert 7 and the insertion cup 1, use will preferably bemade of the insertion cup 1 and the installation and orientation insert7 that are illustrated in FIGS. 8 and 9.

Within the context of the present invention, when assembling the unitcomprising the insertion cup 1 and an installation and orientationinsert 7 (and if appropriate a stationary articular insert 18), it isimportant not to damage the annular receiving structure 6 and theperipheral annular fixing structure 10. In order to achieve a radialclamping of the peripheral annular fixing structure 10 on the outerannular receiving structure 6, it is necessary that the peripheralannular fixing structure 10 has diameter dimensions equal to or lessthan those of the outer annular receiving structure 6.

An assembly method involving expansion and subsequent shrinkage istherefore used, during which the installation and orientation insert 7is heated so as to increase its dimensions, after which the peripheralannular fixing structure 10 is engaged around the receiving face 9 ofthe outer annular receiving structure 6, and, finally, the installationand orientation insert 7 is brought back to room temperature in order toreduce its dimensions.

Such a method permits assembly without blunting or damaging the one ormore locking ribs 15 a-15 d or 17, which thus retain sharp edges for astronger connection between the installation and orientation insert 7and the insertion cup 1.

This method of manufacture by heating also makes it possible to avoidthe abovementioned disadvantages of the method of manufacture by coolingas described in document WO 2006/040483 A1.

On its return to room temperature, a radial clamping of the peripheralannular fixing structure 10 on the outer annular receiving structure 6is obtained. For assembling the unit illustrated in FIG. 14, it ispossible, before fixing the installation and orientation insert 7 on theinsertion cup 1, to insert an articular insert 18 in the concave innerreceiving face 3 of the insertion cup 1.

It is then possible to proceed to a step of sterilization of the unitthus formed and packed in a microbial protection envelope. Asatisfactory sterilization will be achieved by bombardment with gammarays, preferably at a dose of between approximately 25 kGy andapproximately 40 kGy.

It is expressly underlined that the method of manufacture and assemblyof the units in FIGS. 14 and 15, by heating the installation andorientation insert 7 and then returning it to room temperature, can beused with an insertion cup 1 whose outer annular receiving structure 6is not necessarily situated set back from the opening plane P. Themethod of manufacture may thus be the subject of protectionindependently of the position of the outer annular receiving structure 6with respect to the opening plane P of the insertion cup 1.

The present invention is not limited to the embodiments that have beenexplicitly described, and instead it includes the variants andgeneralizations contained within the scope of the attached claims.

1. Method for manufacturing a prosthetic hip acetabulum, comprising thesteps of: a) providing an insertion cup (1) having a concave innerreceiving face (3) with an opening face (5) contained in an openingplane (P), and having an outer annular receiving structure (6), b)providing an installation and orientation insert (7) having a peripheralannular fixing structure (10) designed to cooperate with the receivingface (9) of the outer annular receiving structure (6) by engaging aroundthe outer annular receiving structure (6), c) heating the installationand orientation insert (7) in order to increase the dimensions thereof,d) engaging the peripheral annular fixing structure (10) around thereceiving face (9) of the outer annular receiving structure (6), e)bringing the installation and orientation insert (7) back to roomtemperature in order to reduce the dimensions thereof, so as to achievea radial clamping of the peripheral annular fixing structure (10) on theouter annular receiving structure (6).
 2. The method as claimed in claim1, wherein, before fixing the installation and orientation insert (7) onthe insertion cup (1), the method additionally comprises thesupplementary step b1) of inserting an articular insert (18) in theconcave inner receiving face (3) of the insertion cup (1).
 3. The methodas claimed in claim 2, wherein: the articular insert (18) is made ofceramic, the installation and orientation insert (7) has elastic means(19) for holding the articular insert (18) in the insertion cup (1),when the installation and orientation insert (7) is fixed to theinsertion cup (1), the installation and orientation insert (7) comesinto contact with the articular insert (18) only via the elastic means(19) for holding the articular insert (18) in the insertion cup (1). 4.The method as claimed in claim 2, additionally having a step f) duringwhich the unit thus formed and packed in a microbial protection envelopeis sterilized.
 5. The method as claimed in claim 4, wherein thearticular insert (18) is made of ceramic, and in that the step f) ofsterilization is carried out by bombardment with gamma rays, preferablyat a dose of between approximately 25 kGy and approximately 40 kGy. 6.The method as claimed in claim 1, wherein the installation andorientation insert (7) is made of polyethylene.
 7. The method as claimedin claim 1, wherein: the outer annular receiving structure (6) comprisesa continuous or interrupted peripheral radial shoulder (d) of theannular edge (4), with a receiving face (9) directed toward the outside,the installation and orientation insert (7) has a continuous orinterrupted peripheral annular fixing structure (10) with a connectingface (11) directed toward the inside and designed to cooperate with thereceiving face (9) of the outer annular receiving structure (6).
 8. Themethod as claimed in claim 7, wherein: the receiving face (9) of theouter annular receiving structure (6) has an interrupted peripherallocking groove (14), the connecting face (11) of the peripheral annularfixing structure (10) of the installation and orientation insert (7) hasa plurality of locking ribs (15 a-15 d) which are distributedperipherally and are designed so as to engage in the interruptedperipheral locking groove (14).
 9. The method as claimed in claim 7,wherein: either the receiving face (9) of the outer annular receivingstructure (6) or the connecting face (11) of the peripheral annularfixing structure (10) has a continuous peripheral annular locking groove(16), the other of the connecting face (11) of the peripheral annularfixing structure (10) or the receiving face (9) of the outer annularreceiving structure (6) has a continuous or interrupted peripheralannular locking rib (17) designed so as to engage in the continuousperipheral annular locking groove (16).
 10. The method as claimed inclaim 7, wherein: the peripheral radial shoulder (d) of the annular edge(4) has a thickness (e1) of between approximately 0.7 mm andapproximately 1.2 mm, said interrupted peripheral locking groove (14) orsaid continuous peripheral annular locking groove (16) of the outerannular receiving structure (6) has a radial thickness (e2) of betweenapproximately 0.2 mm and approximately 0.6 mm.
 11. The method as claimedin claim 7, wherein the peripheral radial shoulder (d) of the annularedge (4) has a height (h1) of between approximately 1 mm andapproximately 4 mm.
 12. The method as claimed in claim 8, wherein saidinterrupted peripheral locking groove (14) or said continuous peripheralannular locking groove (16) of the outer annular receiving structure (6)has a height (h2) of between approximately 0.4 mm and approximately 3mm.
 13. The method as claimed in claim 7, wherein the installation andorientation insert (7) and the outer annular receiving structure (6) ofthe insertion cup (1) are designed in such a way that, when theinstallation and orientation insert (7) is fixed to the outer annularreceiving structure (6) of the insertion cup (1), the installation andorientation insert (7) does not protrude outside a substantiallyhemispherical surface (S1) defined by the substantially hemisphericalconvex outer anchoring face (2) of the insertion cup (1).
 14. The methodas claimed in claim 13, wherein the peripheral annular fixing structure(10) of the installation and orientation insert (7) has a radialthickness (e3) substantially equal to or less than the thickness (e1) ofthe radial shoulder (d) of the annular edge (4).
 15. The method asclaimed in claim 1, wherein the annular receiving structure (6) isexternal and is situated set back from the opening plane (P).
 16. Themethod as claimed in claim 1, wherein the installation and orientationinsert (7) has an assembly structure (8) on which an impactor can befixed removably.
 17. The method as claimed in claim 16, wherein theassembly structure (8) comprises a fixation hole (20) with internalthread (21) made in the installation and orientation insert (7),permitting the screwing of a corresponding threaded portion of theimpactor.
 18. The method as claimed in claim 17, wherein the fixationhole (20) is a through-hole able to cooperate with a disconnecting toolhaving a threaded rod which is able to be screwed into the through-holeand which has a distal end designed to bear directly or indirectlyagainst the concave inner receiving face (3) of the insertion cup (1)when the threaded rod is screwed into the through-hole.
 19. The methodas claimed in claim 17, wherein: the installation and orientation insert(7) is designed in such a way that a free space (E1) remains between theinstallation and orientation insert (7) and the bottom of the concaveinner receiving face (3), or, if appropriate, between the installationand orientation insert (7) and the articular insert (18), once theinstallation and orientation insert (7) is fixed to the outer annularreceiving structure (6) of the insertion cup (1), the installation andorientation insert (7) bears in a sealed manner across its connectingface (11) against the receiving face (9) of the outer annular receivingstructure (6), the fixation hole (20) is a through-hole via which thefree space (E1) between the installation and orientation insert (7) andthe bottom of the concave inner receiving face (3) or, if appropriate,between the installation and orientation insert (7) and the articularinsert (18) is brought into communication with the outside and which isdimensioned for leaktight engagement of the end of a syringe.
 20. Themethod as claimed in claim 1, wherein the insertion cup (1) is made ofmetal.